KR20080028980A - Hard-coated body and method for production thereof - Google Patents

Abstract

The invention relates to hard-coated bodies with a single-or multi-layer system containing at least one Ti1-xAlxN hard layer and a method for production thereof. The aim of the invention is to achieve a significantly improved wear resistance and oxidation resistance for such hard-coated bodies. Said hard-coated bodies are characterised in that the bodies are coated with at least one Ti1-xAl xN hard layer, generated by CVD without plasma stimulation present as a single-phase layer with cubic NaCl structure with a stoichiometric coefficient x > 0.75 to x = 0.93 and a lattice constant afcc between 0.412 nm and 0.405 nm, or as a multi-phase layer, the main phase being Ti1-xAlxN with a cubic NaCl structure with a stoichiometric coefficient x > 0.75 to x = 0.93 and a lattice constant afcc between 0.412 nm and 0.405 nm, with Ti1-x AlxN with a wurtzite structure and/or as TiNx with NaCl structure as further phase. Another feature of said hard layer is that the chlorine content is in the range of only 0.05 to 0.9 atom %. The invention further relates to a method for production of the body, characterised in that the body is coated in a reactor at temperatures from 700 °C to 900 °C by means of CVD without plasma stimulation with titanium halides, aluminium halides and reactive nitrogen compounds as precursors, mixed at elevated temperatures. Said coating can be applied to tools made from steel, hard metals, cermets and ceramics, such as drills, millers and indexable inserts.

Description

Hard coating and its manufacturing method {Hard-coated body and method for production}

The present invention relates to a hard material coating having a single layer or a plurality of layers comprising at least one Ti _1-x Al _x N hard-material layer, and a method of manufacturing the same. The coating according to the invention can be used in particular in tools made of steel, hard metal, cermet, and ceramics, such as drills, milling cutters, and cutting inserts. The coating according to the invention has improved friction-wear resistance and oxidation resistance.

The production of a friction-wear protective layer in certain regions of the material system Ti-Al-N is disclosed in WO 03/085152 A2. According to this document it is possible to produce monophasic TiAlN layers having a NaCl structure with an AlN content up to 67%. These layers made by PVD have a lattice constant a _fcc of 0.412 nm to 0.424 nm (R. Cremer, M. Witthaut, A. von Richthofen, D. Neuschuz, Fresenius J. Anal. Chem. 361 (1998) 642 -645). These cubic TiAlN layers have a relatively high hardness and frictional wear resistance. However, when the content of AlN exceeds 67%, a mixture of cubic TiAlN and hexagonal TiAlN forms, and when the AlN ratio exceeds 75%, a softer wurtzite structure that does not exhibit resistance to frictional wear Is formed.

It is also known that as the AlN content increases, the oxidation resistance of the cubic TiAlN layer increases (M. Kawate, A. Kimura, T. Suzuki, Surface and Coatings Technology 165 (2003) 163-167). However, according to the scientific literature on the TiAlN produced by PVD in more than 750 ℃ having a high rate of AlN, i.e. x> 0.75 of Ti _{1 -} mono-phase cubic zirconia on the _x Al _x N TiAlN layer can not be formed, hexagonal It suggests that there is always a burchite structure (K. Kutschej, PH Mayrhofer, M. Kathrein, C. Michotte, P. Polcik, C. Mitterer, Proc. 16th Int. Plansee Seminar, May 30 June 03, 2005, Reutte, Austria, Vol. 2, p. 774-788).

x is a mono-phase up to 0.9 Ti _{1 - x} Al _x N hard material layer has been disclosed that the same may be prepared by plasma CVD (R. Prange, Diss RTHW Aachen , 1999, Fortschritt-Berichte VDI [Progress Reports of the. Association of German Engineers], 2000, Series 5, No. 576, and O. Kyrylov et al., Surface and Coating Techn. 151-152 (2002) 359-364). However, this has the disadvantage of insufficient uniformity of the layer composition and the presence of a relatively high content of chlorine in the layer. In addition, the process is complex and requires a lot of effort.

In order to produce a known Ti _{1 - x} Al _x N hard material layer, the PVD method or the plasma CVD method is used according to the prior art, and the above methods are operated at temperatures below 700 ° C (A. Holing, L. Hultman, M. Oden, J. Sjoen, L. Karlsson, J. Vac. Sci. Technol.A 20 (2002) 5, 1815-1823, and D. Heim, R. Hochreiter, Surface and Coatings Technology 98 (1998) 1553- 1556). However, these methods have the disadvantage that coating by components of complex geometry is difficult. PVD is a highly targeted process and plasma CVD requires a high level of plasma uniformity because the plasma power density directly affects the Ti / Al atomic ratio of the layer. The PVD method, which is currently used almost exclusively in industry, cannot produce monophasic cubic Ti _{1 -x} Al _x N layers with _x exceeding 0.75.

Since the cubic TiAlN layer is a metastable structure, it is fundamentally impossible to manufacture by the conventional CVD method at a high temperature of 1000 ° C or higher, since a mixture of TiN and hexagonal AlN is produced above 1000 ° C.

U.S. Patent 6,238,739 B1 describes the use of aluminum chloride and titanium chloride gas mixtures and NH ₃ and H ₂ , It was disclosed that a Ti _{1 - x} Al _x N layer having x of 0.1 to 0.6 can be obtained at 550 ° C. to 650 ° C. by a thermal CVD process without plasma support. The drawbacks of this particular thermal CVD method are that x is limited to 0.6 or less in the stoichiometry of the layer, and the temperature is limited to 650 ° C. or less. This low coating temperature results in a high chlorine content of up to 12 atomic percent in the layer, which is very detrimental to use (S. Anderbouhr, V. Ghetta, E. Blanquet, C. Chabrol, F. Schuster, C. Bernard, R). Madar, Surface and Coatings Technology 115 (1999) 103-110).

It is an object of the present invention to provide a hard material coating having a single layer or a plurality of layers containing at least one layer of Ti _1-x Al _x N hard material having improved abrasion resistance and oxidation resistance.

This object is achieved by the claimed features of the present invention.

The hard material coating according to the present invention is coated with at least one layer of Ti _1-x Al _x N hard material produced by CVD without plasma stimulation, the layer having a stoichiometry coefficient x of 0.75 <x ≦ 0.93 and lattice constant a _fcc is present as a monophasic layer of cubic NaCl structure with 0.412 nm to 0.405 nm, or its main phase has stoichiometric coefficient x of 0.75 <x ≤0.93 and lattice constant a _fcc of 0.412 nm Ti _1-x Al _x N having a cubic NaCl structure of from 0.405 nm, and Ti _1-x Al _x N of a brookite structure and / or TiN _x of a NaCl structure It is characterized in that the multi-phase Ti _1-x Al _x N hard material layer comprising an additional phase (additional phase). This Ti _1-x Al _x N hard material layer is further characterized by a chlorine content of only 0.05 to 0.9 atomic percent. It is advantageous if the chlorine content of the Ti _1-x Al _x N hard material layer is only 0.1 to 0.5 atomic% and the oxygen content is 0.1 to 5 atomic%.

The hardness value of the Ti _1-x Al _x N hard material layer is 2500 HV to 3800 HV.

According to the invention, up to 30% by weight of amorphous layer components can be included in the Ti _1-x Al _x N hard material layer.

According to the present invention, the layer present on the body has a significantly improved oxidation resistance and a high hardness of 2500 HV to 3800 HV compared to the prior art, due to the high AlN ratio on the cubic Ti _1-x Al _x N phase. Bars, such a combination of hardness and oxidation resistance have not been achieved so far and result in good friction-wear resistance, in particular very high friction-wear resistance at high temperatures.

For the production of the coating of the present invention, the present invention is to coat the body by CVD without plasma stimulation in the temperature range of 700 ℃ to 900 ℃ in the reactor, mixed with titanium halogenide (titanium halogenide) at elevated temperature , Aluminum halogenide, and a reactive nitrogen compound are used as precursors.

According to the invention, NH ₃ and / or N ₂ H ₄ can be used as the reactive nitrogen compound.

Such precursors are preferably mixed in the reactor just before the deposition zone.

Mixing of the precursors is carried out in a temperature range of 150 ° C. to 900 ° C. according to the invention.

This coating process is preferably carried out in a pressure range of 10 ² Pa to 10 ⁵ Pa.

By using the method according to the invention, a Ti _1-x Al _x N layer having a NaCl structure can be produced at a pressure of 10 ² Pa to 10 ⁵ Pa at 700 ° C. to 900 ° C. using a relatively simple thermal CVD process. have. Both known Ti _1-x Al _x N layer compositions of x &lt; The method of the present invention allows uniform coating even for components of complex geometries.

Hereinafter, the present invention will be described in more detail with reference to Examples, and the following Examples do not limit the present invention.

Figure 1 shows a diffraction pattern of the Ti _{1 - x} Al _x N hard material layer according to an embodiment of the present invention,

2 is Ti ₁ according to another embodiment of the present _invention shows the diffraction pattern of the Al _{x x} N hard material layer.

Example 1

Ti _{1 - x} Al _x N layers were deposited on the WC / Co hard metal cutting insert by thermal CVD method according to the present invention. To this end, under a pressure of 800 ° C., 1 kPa, into a hot-wall CVD reactor with an internal diameter of 75 mm, 20 ml / min AlCl ₃ , 3.5 ml / min TiCl ₄ , 1400 ml / min H ₂ , 400 ml / min of argon gas mixture was introduced.

A mixture of 100 ml / min NH ₃ and 200 ml / min N ₂ was passed into the reactor with a second gas feed. The mixing of these two gas streams was done 10 cm in front of the substrate carrier. After 30 minutes of coating time, a black gray layer of 6 μm in thickness was obtained.

Sweeping insideonseu (sweeping incidence) a X- ray films results only cubic Ti ₁ carried out _{in-the x} Al _x N sangman been discovered (see the X- ray diffraction pattern (diffractogram) in Fig. 1).

The lattice constant a _fcc was measured at 0.4085 nm. The atomic ratio of Ti: Al was 0.107 as measured by WDX. As a result of measuring the chlorine and oxygen content, chlorine was 0.1 atomic% and oxygen was 2.0 atomic%.

The stoichiometric coefficient x was calculated to be 0.90. The hardness of the layer was 3070 HV [0.05], as measured by a Vickers hardness tester. The Ti _{1 - x} Al _x N layer showed oxidation resistance up to 1000 ° C. in air.

Example  2

First, by a known titanium nitride layer having a thickness 1㎛ standard CVD process, Si ₃ N ₄ at 950 ℃ It was applied to a cutting insert made of cutting ceramic. A black gray layer was then deposited by the CVD method according to the invention at 1 kPa pressure and 850 ° C. using the gas mixture described in Example 1.

X- ray analysis films, Ti ₁ having the NaCl structure _was confirmed by the _x Al _x N and called heterologous (heterogeneous) mixture of the AlN in the difference tree structure exists. In the X- ray diffraction structure of Figure 2, the cubic Ti _{1 - x} Al _x N in a reflex reflex (reflex) is represented by c, hexagonal AlN (called the difference bit structure) was represented by h. The ratio of _x Al _x N was dominant _- cubic Ti ₁ in the layer.

The lattice constant a _fcc of the cubic phase was measured to be 0.4075 nm. Second, the hexagonal AlN phase was measured with lattice constants a = 0.3107 nm, and c = 0.4956 nm. The hardness of the layer was measured with a Vickers hardness tester, and the hardness was 3150 HV [0.01]. The biphase Ti _1-x Al _x N layer exhibited oxidation resistance up to 1050 ° C. in air.

Claims (10)

A hard material coating having a single layer or a plurality of layers comprising at least one layer of Ti _1-x Al _x N hard material produced by CVD without plasma stimulation, The Ti _1-x Al _x N hard material layer exists as a monophasic layer of cubic NaCl structure having a stoichiometric coefficient x of 0.75 <x ≦ 0.93 and lattice constant a _fcc of 0.412 nm to 0.405 nm, or the Ti _{1- The x} Al _x N hard material layer is a plural layer composed of Ti _1-x Al _x N having a cubic NaCl structure in which the main phase has a stoichiometric coefficient x of 0.75 <x ≤ 0.93 and a lattice constant a _fcc of 0.412 nm to 0.405 nm. Ti _1-x Al _x N and / or TiN _x in NaCl structure A hard material coating comprising a plurality of additional layers, wherein the chlorine content of the Ti _1-x Al _x N hard material layer is 0.05 to 0.9 atomic%. The method of claim 1, Hard material coating, characterized in that the chlorine content of the Ti _1-x Al _x N hard material layer is 0.1 to 0.5 atomic%. The method of claim 1, Hard material coating, characterized in that the oxygen content of the Ti _{1 - x} Al _x N hard material layer is 0.1 to 5 atomic%. The method of claim 1, Hard material coating, characterized in that the hardness of the Ti _1-x Al _x N hard material layer is 2500 HV to 3800 HV. The method of claim 1, And wherein the Ti _1-x Al _x N hard material layer comprises 0 to 30 weight percent of an amorphous layer component. A method of making a hard material coating having a single layer or a plurality of layers comprising at least one Ti _1-x Al _x N hard material layer, Coating the body by CVD without plasma stimulation in a temperature range of 700 ° C. to 900 ° C. in the reactor, and using titanium halogenide, aluminum halogenide, and reactive nitrogen compounds mixed at elevated temperatures as precursors The manufacturing method to make. The method of claim 6, NH ₃ and / or N ₂ H ₄ as a reactive nitrogen compound. The method of claim 6, Wherein said precursors are mixed in the reactor just before the deposition zone. The method of claim 6, The precursors are mixed, characterized in that in the temperature range of 150 ℃ to 900 ℃. The method of claim 6, The coating process is characterized in that carried out in a pressure range of 10 ² Pa to 10 ⁵ Pa.

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